embedding examples from the paper "Functional Reactive Programming, Refactored"

[madjestic]

Hey guys,

I am finally reading the paper carefully and managing to get most code working, special thanks to the github repo matching the code from the paper. Great read by the way!

The issue that I am having is running the embed function using the code from the paper/repo, e.g.:

(embed game $ replicate 23 ())

<interactive>:20:1: error:
    • No instance for (Show1 (ReaderT GameSettings m0))
        arising from a use of ‘print’
    • In a stmt of an interactive GHCi command: print it

as is mentioned on page 6 of "Submission to Haskell Symposium 2016" paper. I understand from the error message that I need to provide an instance for Show1 but it's not immediately clear how to do it. Could somebody show how to do it in this case or suggest a better alternative?

data GameSettings
  =  GameSettings
  { leftPlayerPos  :: Int
  , rightPlayerPos :: Int
  } deriving Show
  
type GameEnv m = WriterT [String] (ReaderT GameSettings m)
...

Thanks!

[madjestic]

I think I figure this out:

embed (runReaderS(runWriterS game)) $ replicate 23 (GameSettings 0 5, ())
> [(["Ball at 1"],1),(["Ball at 2"],2),(["Ball at 3"],3),(["Ball at 4"],4),(["Ball at 1"],1),(["Ball at 2"],2),(["Ball at 3"],3),(["Ball at 4"],4),([],5),([],6),([],7),([],8),([],9),([],10),([],11),([],12),([],13),([],14),([],15),([],16),([],17),([],18),([],19)]

It might be useful stressing this, perhaps in an appendix or under a dagger? I understand that the paper is cutting a few corners for the sake of sticking to the goal, clarity and brevity, as such expressions might scare a reader away or distract with syntax noise.

I really like how, mostly, you can read the paper and play with the code that evolves naturally, consistently and mostly works! The best MSF tutorial that I have found so far. I would go as far as humbly suggest that the paper might be worth updating and turning into a tutorial?

Cheers!